The present invention relates to a method of transmitting a command to reproduce an audio-only disk-shaped recording medium to a device driver on the basis of a request from application software.
As is well known, in a computer system, data and information on attributes of the data are handled in a unit of a file and stored in a device such as an Hard Disk Drive (HDD) or the like. The file is managed by a so-called file system. The file system implemented provides a correspondence between a physical recording position of the data and attribute information actually stored in the device such as the HDD or the like and file manipulation from application software, for example.
Consequently data manipulation such as reading data from the HDD, writing data to the HDD, and deleting data from the HDD by the application software positioned at a higher level than the device, for example, is simplified.
That is, even when the application software does not know the physical recording position of the data and attribute information actually stored in the device, the application software properly performs data manipulation such as reading data from the HDD, writing data to the HDD, and the like by calling a command or a function provided in advance by the system side by a system call, for example, and outputting the command or the function to the file system. When certain application software is to read a specified file on the basis of a user operation, for example, a command to read data is issued by a system call, and in response to the command, control is effected on the device to read the specified file from the HDD.
The command called as described above, for example, is standardized to be a common command usable by various applications. It can therefore be said that an instruction for file manipulation by application software is converted to a unique instruction by a system call as mentioned above, for example. The system call for such file manipulation is enabled on a precondition that the file is managed by the file system in a layer lower than that of the application software.
Incidentally, as file system corresponding to the HDD, File Allocation Table (FAT) or the like is known.
Drives capable of reproducing CD-ROM have recently spread widely as a block device other than the HDD. Generally, a computer system having a CD-ROM drive as a device can install appropriate application software, middleware, and the like therein and thus reproduce a disk medium in a CD format. That is, the computer system can reproduce CD-DA (Digital Audio) in addition to CD-ROM. As is well known, CD-ROM is a disk medium, having data recorded thereon, for reproduction only. CD-DA is for audio data only and is a disk medium on which digital audio data in a format of a sampling frequency of 44.1 kHz and 16-bit quantization is recorded for reproduction only.
As a logical format of CD-ROM described above, ISO 9660 is defined. Under the format of ISO 9660, a file system for ISO 9660 is defined.
For example, for a CD-ROM in the ISO 9660 format, a file system generated on the basis of contents of a path table recorded on the CD-ROM is mounted, as is well known.
Also in this case, application software at a higher level can perform manipulation such as reading of data recorded on the CD-ROM and the like by a system call as mentioned above, for example, using the above file system for ISO 9660. That is, the application software can manipulate the data recorded on the CD-ROM through an Application Program Interface (API) similar to that for the HDD.
This eliminates the need for preparing, for each piece of application software, a program for direct file manipulation with the position of data recorded on the HDD or the CD-ROM taken into consideration. Therefore, design of application software for processing data recorded on the CD-ROM, for example, can be correspondingly simplified.
As described above, some disk drives capable of reproducing disk media in the CD format such as CD-ROM drives can read data not only from a CD-ROM but also from a CD-DA.
Application software operating on a CD-DR performs operation, for example, the software controls reproduction of the CD-DA, whereby audio data recorded on the CD-DA loaded in a CD-ROM drive is read to be, for example, reproduced and outputted or recorded on an HDD or the like.
In the present situation, however, the file system is provided for CD-ROM as described above, whereas no file system is provided for CD-DA.
For example the format of CD-ROM is originally defined on an assumption that CD-ROM records data to be processed by a computer system. Therefore file systems for CD-ROM including for example the above-described file system for ISO 9660 were implemented from the beginning.
On the other hand, CD-DA is originally based on an assumption that CD-DA is only reproduced by an audio apparatus such as a CD player or the like. Therefore, a file system for CD-DA has not been incorporated in a system such as an OS, for example, and no file system for CD-DA is implemented in the present situation either.
Thus no file system for CD-DA being implemented means that unlike the case of manipulation of data on a CD-ROM, it is not possible to effect control by a unique command using a system call provided by the computer system.
Hence, a program of application software for realizing some function aimed at CD-DA, for example, is created on this assumption.
That is, the program is created such that the application software can directly control a device for CD-ROM or the like and perform manipulation such as reading of data from a CD-DA and the like. For example, the application software is configured to issue commands that can directly control the device. Thus, the creation and design of a program of application software operating on CD-DA is correspondingly more difficult.